1. Field of the Invention
The present invention relates to a photo resist composition, and particularly to a chemical amplified photoresist composition including polymers, and to a method for lithography to which the photoresist composition is applied.
2. Related Prior Art
Integral circuit layering is crucial in semiconductor industries such that the number of integral layers on an integral circuit must be maximized. Therefore, narrower wire widths for lithography are required. To achieve better resolution, light sources with shorter wavelengths or exposure systems with larger numerical apertures are applied.
Recently, a tetrapolymer iBMA-MMA-tBMA-MMA (poly isobornyl methacrylate-methyl methacrylate-t-butyl methacrylate-methacrylic acid) is reported to be a possible resin system for ArF resist: 
For such polymers, there are still some disadvantages, for example, low etch resistance and bad adhesion due to the four monomer composition. Therefore, a new resin for the compositions of resists is eager to be developed.
U.S. Pat. Nos. 6,271,412 and 6,280,898 and Japanese Patent Publication No. 2001-242627 have disclosed different monomers for synthesizing photosensitive polymers, which can form photoresist compositions and then be applied to semiconductor component manufacturing.
The present invention provides a chemical amplified photoresist composition, which comprises a polymer containing a novel lactone alicyclic unit. And the photoresist comprising the polymer provide well-balanced outcome of etching resistance and substrate adhesion.
An object of the present invention is to provide a chemical amplified photoresist composition, which is suitable for lithography processes and can exhibit excellent resolution, picture sharpness and photosensitivity.
Another object of the present invention is to provide a method for manufacturing semiconductor devices by lithography process, which is particular suitable for ArF, KrF or the like light source and can exhibit excellent resolution, figures and photosensitivity.
Accordingly, the chemical amplified photoresist composition includes a polymer having repeated units of the formula (II), 
wherein R1 is H, haloalkyl group or C1-C4 alkyl group; R2 is hydroxyl group, C1-C8 alkoxy group or C1-C8 thioalkyl group; G is (CH2)n, O or S, wherein n is 0, 1, 2, 3 or 4; Rc is a lactone group; and m is 1, 2 or 3.
The chemical amplified photoresist composition can further optionally include a photo-acid generator (PAG), an acid quencher, an additive, a solvent, etc.
The chemical amplified photoresist composition of the present invention can be applied to general lithography processes, and particularly to the process of ArF, KrF or the like light source, whereby excellent resolution, figures and photosensitivity can be achieved. Such processes are well known by those skilled in this art.
The present invention also relates to a method for manufacturing semiconductor devices by lithography, to which the above chemically amplified photoresist composition is applied, and particularly for the exposure process with ArF, KrF or the like light source.
The chemical amplified photoresist composition of the present invention includes a polymer having a repeated unit of the formula (II), which is essentially formed through a reaction involving a compound of the following formula (I), 
wherein R1 is H, haloalkyl group or C1-C4 alkyl group; R2 is hydroxyl group, C1-C8 alkoxy group or C1-C8 thioalkyl group; G is (CH2)n, O or S, wherein n is 0, 1, 2, 3 or 4; Rc is a lactone group; and m is 1, 2 or 3.
This reaction can be performed by self-polymerization of the above compound or copolymerizing the above compound with other vinyl monomers in the presence of catalysts.
One of the methods for preparing the formula (I) compound is shown below, 
wherein R1, R2 and G are defined as the above.
In Step 1, a proper diene compound such as butadiene, cyclopentadiene, furan and thiophene, reacts with maleic anhydride to perform the Diels-Alder reaction. Then, the acid anhydride adducts are reduced under the well-known conditions in the second Step 2. Preferably reaction is carried out using sodium boron hydride in dried polar solvent such as dimethylformamide or tetrahydrofuran. In Step 3, peroxide is provided to oxidize the double-bond compound into an epoxide. In Step 4, the epoxide reacts with a proper nucleophilic reagent such as water, alcohol and thiol, to perform a ring opening addition reaction under an acidic environment and then obtaining a hydroxyl derivative can be obtained. In Step 5, the hydroxyl derivative reacts with (alkyl)acryloyl chloride or acryloyl chloride to perform esterification resulting in and finally the compound of the formula (I) is obtained. Detailed procedures for preparing the compound of the present invention are described in the preferred embodiments.
The compounds of the formula (I) can be polymerized or copolymerized with other vinyl monomers to produce various polymers with or without the assistance of catalysts. Particularly, when being applied to the 193 nm processes, the vinyl monomers preferably have no aryl group to enable the light to pass therethrough. Below are some examples of vinyl monomers, wherein R3 is H, haloalkyl group, haloalkyl group or C1-C4 alkyl group. 
According to the compound of the formula (I), the polymer having a repeated unit of the formula (II) can be synthesized through self-polymerization or copolymerization, 
wherein R1, R2, G, Rc and m are defined as the above.
The structure unit of the polymer or copolymers polymerized or copolymerized from compound (I) can be the following formula (III), formula (IV) or formula (V), 
wherein R, Rxe2x80x2 and Rxe2x80x3 each independently is H, haloalkyl group or methyl group. In the structure unit of formula (III) and (IV) g+h+i=1, more preferably g/(g+h+i)=0.01-0.8, h/(g+h+i)=0.01-0.8, i/(g+h+i)=0.01-0.8; in the structure unit of formula (V) g+h+i+j=1, more preferably g/(g+h+i+j)=0.01-0.5, h/(g+h+i+j)=0.01-0.8, i/(g+h+i+j)=0.01-0.8, j/(g+h+i+j)=0.01-0.8.
The above polymers can be used individually, or by mixing with one or more thereof.
The polymer of the present invention is preferably soluble in organic solvents, and has a glass transfer temperature (Tg) ranging from 50 to 220xc2x0 C., molecular weight ranging from 1,000 to 500,000, and degradation temperature (Td) greater than 80xc2x0 C.
The method of polymerization is not restricted, and is preferably done by mixing the above monomers in the existence of catalysts. The catalysts can be those well known by one skilled in this art, and preferably 2,2xe2x80x2-azo-bis-isobutyronitrile (AIBN) or dimethyl-2,2xe2x80x2-azo-bis-isobutyrate radical initiator (V-601).
The chemical amplified photo resist composition of the present invention can further include a photo-acid generator (PAG), an acid quencher, an additive or a solvent.
The above photo-acid generator is not restricted, but can generate acids under ultraviolet or other radiation sources, and be stable before exposure. The preferred photo-acid generators are as follows: 
The above photo-acid generators can be used individually, or by mixing with one or more thereof. The photo-acid generator is usually added at 1.0-20 parts per 100 parts of resin in weight, and preferably 0.5-7 parts.
The chemical amplified photoresist composition of the present invention can further include acid quencher to adjust the diffusion of acid. The proper acid quenchers are tetrabutylammonium hydroxide, tetrabutylammonium lactate, tributylamine, trioctylamine, triethanolamine, tris[2-(2-methoxyethoxy)ethyl]amine, N-(2,3-dihydroxypropyl)piperidine, N-(2-hydroxyethyl)piperidine, morpholin, N-(2-hydroxyethyl)morpholin, N-(2-hydroxyethyl)pyrrolidine, N-(2-hydroxyethyl)piperazine, etc. The acid quencher is usually added at 0.001-10 parts per part of the photo-acid generator in weight, and preferably 0.01-1 part.
The additive of the present invention is not restricted, and can be optionally added or not. Proper amounts of sensitizers, dissolution inhibitors, surfactants, stabilizers, dyes or other resins may be a good additive to improve the characteristics of the photpresist composition.
There is no special limit to the solvent of the chemical amplified photoresist compositions of the present invention. Preferably, the solvent suitable for the chemical amplified photoresist compositions of the present invention is higher alcohol (e.g. n-octanol), glycolic acid and its derivatives (e.g. methyl lactate, ethyl lactate and ethyl glycolate), glycolic ether and its derivatives (e.g. glycolic ethyl acetate, glycolic methyl acetate, glycerol methyl acetate), ketoesters (e.g. methyl acetoacetate, ethyl acetoacetate), alkoxy carboxylates (ethyl 2-ethoxyacetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, or methyl ethoxypropionate), ketones (methyl ethyl ketone, methyl pentyl ketone, acetylacetone cyclopentone, cyclohexone, or 2-hepatone) ketoethers (e.g. diacetoalcohol methyl ether), ketoalcohols (e.g. acetoalcohol or diacetone ), alcohol ethers (e.g. glycolic butyl ether or propylene glycol ethyl ether)amides (e.g. dimethylacetamide or dimethyl formamide), ethers (e.g. phenyl ether or triethylene glycol dimethyl ether) or mixture thereof. Preferably, the solvent of the chemical amplified photoresist is n-octyl alcohol, propylene glycol methyl ether acetate, ethyl 3-ethoxypropionate, ethyl 2-ethoxyacetate, methyl 3-methoxypropionate, methylethoxypropionate, methyl ethyl ketone, methylpentylmethyl ketone, cyclopentanone, methyl acetate, ethyl acetate, glycolic butyl ether propylene glycol ethyl ether or mixture thereof.
The solvent is usually added at 200-2,000 parts per 100 parts of resin in weight, and preferably 400-1,000 parts.
The chemical amplified photoresist composition of the present invention can be prepared by first dissolving the polymer in the solvent and then dissolving the other components therein, or by first dissolving the other components which are mixed together previously in the solvent and then dissolving the polymer therein.
Impurities in the chemical amplified photo resist composition, for example, metals and halogens, should be minimized. Therefore, the components can be purified previously, or the produced chemical amplified photoresist composition is purified before using.
In addition to the traditional lithography processes, the chemical amplified photoresist composition of the present invention can be particularly applied to the 193 nm process.
When applying the chemical amplified photoresist composition, lithography general procedures are performed. The photoresist composition is first spread on silicon substrates or other substrates by spinning, spraying, rolling, etc. Usually, the substrate is then baked on a thermoplate to remove the solvent and then exposed with masks to form patterns.
The development solutions for the exposed resist coating can be an alkali solution, for example, ammonia, triethylamine, dimethylaminomethanol, tetramethylammonium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, trimethylhydroxylethylamonium hydroxide, etc.
The resolution, shape and sensitivity of the chemical amplified photoresist composition of the present invention are good. Besides, the depth of focus, exposure border and removing border are excellent.